javascript onbeforecopy Description

Fires just before a user-initiated Copy command (via the Edit menu, a keyboard shortcut, or a context menu) completes the task of moving the selected content to the system clipboard. At this point in the copy sequence, a function invoked by this event handler can perform additional or substitute processing for the normal system copy action. For example, additional information from the element, such as effective style information of the element containing selected text), can be preserved in the IE clipboardData object for later processing with the help of the onbeforepaste event handler. Canceling the onbeforecopy event does not prevent user copying of a selection.